Selective Deposition Of Silicon Using Deposition-Treat-Etch Process

ABSTRACT

Methods for selective silicon film deposition on a substrate comprising a first surface and a second surface are described. More specifically, the process of depositing a film, treating the film to change some film property and selectively etching the film from various surfaces of the substrate are described. The deposition, treatment and etching can be repeated to selectively deposit a film on one of the two substrate surfaces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/515,582, filed Jun. 6, 2017, the entire disclosure of which is herebyincorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to methods of selectivelydepositing silicon films. In particular, the disclosure relates toprocesses for selectively depositing a silicon layer with a multi-stagedeposition-treat-etch process.

BACKGROUND

Forming films on a substrate by chemical reaction of gases is one of theprimary steps in the fabrication of modern semiconductor devices. Thesedeposition processes include chemical vapor deposition (CVD) as well asplasma enhanced chemical vapor deposition (PECVD), which uses plasma incombination with traditional CVD techniques.

Selective deposition processes are becoming more frequently employedbecause of the need for patterning applications for semiconductors.Traditionally, patterning in the microelectronics industry has beenaccomplished using various lithography and etch processes. However,since lithography is becoming exponentially complex and expensive theuse of selective deposition to deposit features is becoming much moreattractive.

As device sizes continue to decrease to less than the 10 nm regime,traditional patterning processes using photolithography technology isbecoming more challenging. Non-precise patterning and degraded deviceperformance are more prevalent at lower device sizes. Additionally, themultiple patterning technologies also make fabrication processescomplicated and more expensive.

Therefore, there is a need in the art for methods to selectively deposita film onto one surface over a different surface.

SUMMARY

One or more embodiments of the disclosure are directed to a method ofselectively depositing a film wherein a substrate is provided having afirst surface and a second surface. The substrate is exposed to a silaneand a deposition plasma to deposit a silicon film on the first surfaceand the second surface, the silicon film having different properties onthe first surface and on the second surface. The silicon film is exposedto a treatment plasma to modify a structure, composition or morphologyof the silicon film on one or more of the first surface or the secondsurface, the treatment plasma comprising plasmas of one or more of Ar,He, or H₂. The film is etched from the first surface and the secondsurface to remove substantially all of the film from the second surfaceand leave at least some of the silicon film on the first surface. Thedeposition, treatment and etching are repeated to form a filmselectively on the first surface over the second surface.

Additional embodiments of the disclosure are directed to a method ofselectively depositing a film wherein a substrate is provided having afirst surface consisting essentially of silicon and a second surfacecomprised of at least one different material. The substrate is exposedto SiH₄ and a hydrogen plasma to deposit a silicon film on the firstsurface and the second surface, the silicon film having differentproperties on the first surface and on the second surface. The siliconfilm is exposed to a treatment plasma to modify a structure, compositionor morphology of the silicon film on one or more of the first surface orthe second surface, the treatment plasma comprising plasmas of one ormore of Ar, He, or H₂. The film is etched from the first surface and thesecond surface with a thermal etch to remove substantially all of thefilm from the second surface and leave at least some of the silicon filmon the first surface. The deposition, treatment and etching are repeatedto form a film selectively on the first surface over the second surface.

Further embodiments of the disclosure are directed to a method ofselectively depositing a film wherein a substrate is provided having afirst surface consisting essentially of silicon and a second surfacecomprised of at least one different material. The substrate is exposedto SiH₄ and a hydrogen plasma to deposit a silicon film on the firstsurface and the second surface, the silicon film having differentproperties on the first surface and on the second surface. The siliconfilm is exposed to a treatment plasma to modify a structure, compositionor morphology of the silicon film on one or more of the first surface orthe second surface, the treatment plasma comprising plasmas of one ormore of Ar, He, or H₂. The film is etched from the first surface and thesecond surface with a plasma etch to remove substantially all of thefilm from the second surface and leave at least some of the silicon filmon the first surface. The deposition, treatment and etching are repeatedto form a film selectively on the first surface over the second surface.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

The Figure shows a process flow in accordance with one or moreembodiments of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the invention, it isto be understood that the invention is not limited to the details ofconstruction or process steps set forth in the following description.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/orbake the substrate surface. In addition to film processing directly onthe surface of the substrate itself, in the present invention, any ofthe film processing steps disclosed may also be performed on anunderlayer formed on the substrate as disclosed in more detail below,and the term “substrate surface” is intended to include such underlayeras the context indicates. Thus for example, where a film/layer orpartial film/layer has been deposited onto a substrate surface, theexposed surface of the newly deposited film/layer becomes the substratesurface.

Embodiments of the disclosure provide methods of selectively depositinga film (e.g., silicon) on a substrate with varied surface compositions.Some embodiments advantageously provide methods involving cyclicdeposition-treatment-etch processes that can be performed in a clustertool environment. Some embodiments advantageously deposit silicon filmson silicon surfaces over other surfaces.

Without being bound by any particular theory of operation, it isbelieved that the nucleation of materials (e.g., Si) is different ondifferent surfaces. Therefore, the nucleation on a film with differentdegrees of crystallinity will be different. Additionally, the etch rateof materials (e.g., Si) will be different on different surfaces. Someembodiments advantageously provide methods that use plasma to etchmaterials (e.g., Si) faster on certain surfaces than on other surfaces.Some embodiments advantageously use the different etch rates ondifferent surfaces to create selective deposition of a silicon film bycycling the deposition-treatment-etch process.

The Figure shows an exemplary processing method 100 in accordance withone or more embodiments of the disclosure. A substrate having a firstsurface and a second surface is provided for processing at 110. As usedin this regard, the term “provided” means that the substrate is placedinto a position or environment for further processing. The first surfaceand the second surface are different materials. For example, one of thesurfaces may be silicon and the other a metal. In some embodiments, thefirst surface and the second surface have the same chemical compositionbut different physical properties (e.g., crystallinity).

The first surface can be any suitable material including, but notlimited to, metallic films. In some embodiments, the first surface ismetallic comprising one or more of silicon, tungsten, cobalt, copper,ruthenium, palladium, platinum, nickel, chromium, manganese, iron,zirconium, molybdenum, niobium, silver, hafnium, tantalum, or alanthanide. In some embodiments, the first surface consists essentiallyof silicon. As used in this manner, the term “consists essentially of”means that the surface is greater than or equal to about 95%, 98% or 99%silicon on an atomic basis.

The second surface can be any suitable surface that is different fromthe first surface. The difference between the first surface and thesecond surface can be based on film composition or on some physicalproperty of the film. In some embodiments, the second surface comprisesa metal boride, metal oxide, metal nitride, metal carbide, metaloxycarbide, metal oxynitride, metal oxyboride, metal boronitride, metalborocarbide, metal carbonitride, metal oxycarbonitride, metalborocarbonitride, metal borooxynitride, metal oxyborocarbonitride, orcombinations thereof. In some embodiments, the second surface comprisesa dielectric material having either a low dielectric constant (k<5) or ahigh dielectric constant (k>=5). In some embodiments, the second surfacecomprises one or more of silicon oxide, silicon nitride.

In some embodiments, the first surface comprises a metal surface and thesecond surface comprises a similar metal as the first surface withdifferent crystallinity than the first surface. In some embodiments, thefirst surface and the second surface comprise dielectric materials withdifferent crystal structures, densities and/or surface terminations.

While the description of the process in the Figure is presented withrespect to a substrate with a first surface comprising silicon and asecond surface comprising one or more of silicon oxide or siliconnitride, those skilled in the art will recognize that this is merelyrepresentative of one possible configuration and that other combinationsare within the scope of the disclosure. The substrate is exposed at 120to a silane and a deposition plasma. For the purposes of thisdisclosure, this exposure is referred to as the deposition. In someembodiments, the silane comprises at least one species with the formulaSi_(n)H_(2n+2). In some embodiments, the silane consists essentially ofSiH₄. In some embodiments, the silane consists essentially of Si₂H₆. Insome embodiments, the silane consists essentially of dichlorosilane,SiH₂Cl₂. As used in this manner, the term “consists essentially of”means that the silane is greater than or equal to about 95%, 98% or 99%of the stated species on a weight basis. In some embodiments, the silanecomprises a silicon halide species where the halogen atoms comprise oneor more of Cl, Br and I. In some embodiments, the silicon halidecomprises substantially no fluorine atoms. As used in this manner, theterm “substantially no fluorine atoms” means that the composition of thehalogen species is less than or equal to about 95%, 98% or 99% fluorine,on an atomic basis.

In some embodiments, the deposition plasma comprises one or more of Ar,He, H₂ or N₂. In some embodiments, the deposition plasma consistsessentially of Ar. In some embodiments, the deposition plasma consistsessentially of He. In some embodiments, the deposition plasma consistsessentially of H₂. In some embodiments, the deposition plasma consistsessentially of N₂. As used in this manner, the term “consistsessentially of” means that the deposition plasma is greater than orequal to about 95%, 98% or 99% of the stated species on an atomic basis.

The deposition plasma can be a conductively-coupled plasma (CCP) orinductively coupled plasma (ICP) and can be a direct plasma or a remoteplasma. In some embodiments, the deposition plasma has a power in therange of about 0 W to about 2000 W. In some embodiments, the minimumplasma power is greater than 0 W, 10 W, 50 W or 100 W.

The temperature during deposition 120 can be any suitable temperaturedepending on, for example, the precursor(s) and/or deposition plasma(s)being used. In some embodiments, the deposition temperature is in therange of about 100° C. to 500° C., or in the range of about 150° C. toabout 450° C., or in the range of about 200° C. to about 400° C.

The processing chamber pressure during deposition 120 can be in therange of about 100 mTorr to 300 Torr, or in the range of about 200 mTorrto about 250 Torr, or in the range of about 500 mTorr to about 200 Torr,or in the range of about 1 Torr to about 150 Torr.

As identified previously, the nucleation of the silicon film on thefirst surface and the second surface may impact the thickness as well asthe physical properties of the film deposited as a result of thesilane/plasma exposure at 120 on the first surface and the secondsurface. In some embodiments, the crystallinity of the silicon filmdeposited on the first surface and the second surface is different afterdeposition.

The film deposited can be any suitable thickness before moving to thetreatment process. In some embodiments, the thickness of the depositedfilm is greater than or equal to about 5 Å, 10 Å, 15 Å, 20 Å or 25 Åbefore moving to the treatment process. In some embodiments, thethickness of the deposited film is less than or equal to about 100 Å, 90Å, 80 Å, 70 Å, 60 Å or 50 Å before moving to the treatment process.

After deposition, the substrate is exposed to a treatment plasma at 130to modify a structure, composition or morphology of the silicon film onthe first surface and/or the second surface. For the purposes of thisdisclosure, this exposure is referred to as the treatment.

In some embodiments, the treatment plasma comprises one or more of Ar,He, or H₂. In some embodiments, the treatment plasma consistsessentially of Ar. In some embodiments, the treatment plasma consistsessentially of He. In some embodiments, the treatment plasma consistsessentially of H₂. As used in this manner, the term “consistsessentially of” means that the treatment plasma is greater than or equalto about 95%, 98% or 99% of the stated species on an atomic basis. Insome embodiments, the treatment plasma is the same as the depositionplasma. In some embodiments, the treatment plasma is different than thedeposition plasma.

The treatment plasma can be a conductively-coupled plasma (CCP) orinductively coupled plasma (ICP) and can be a direct plasma or a remoteplasma. In some embodiments, the plasma has a power in the range ofabout 0 to about 2000 W. In some embodiments, the minimum plasma poweris greater than 0 W, 10 W, 50 W or 100 W.

The temperature during treatment 130 can be any suitable temperaturedepending on, for example, the treatment plasma(s) being used. In someembodiments, the treatment temperature is in the range of about 100° C.to 500° C., or in the range of about 150° C. to about 450° C., or in therange of about 200° C. to about 400° C.

The processing chamber pressure during treatment 130 can be in the rangeof about 100 mTorr to 300 Torr, or in the range of about 200 mTorr toabout 250 Torr, or in the range of about 500 mTorr to about 200 Torr, orin the range of about 1 Torr to about 150 Torr.

As identified previously, the structure, composition or morphology ofthe silicon film on the first surface and the second surface will bedifferent as a result of the treatment plasma exposure at 130. In someembodiments, the crystallinity of the silicon film on the first surfaceand the second surface is different after treatment. In someembodiments, the crystallinity of the silicon film on the first surfaceand the second surface is different before treatment and after treatmentthe difference between the crystallinities is greater than beforetreatment.

After treatment, the substrate is etched at 140 to remove substantiallyall of the silicon film from the second surface and leave at least someof the silicon film on the first surface. As used in this manner, theterm “substantially all” means that enough of the film from the secondsurface has been removed to provide a nucleation delay for a subsequentdeposition process. In some embodiments, removing substantially all ofthe film from the second surface means that at least about 95%, 98% or99% of the film from the second surface has been etched or removed.

In some embodiments, the film is etched with a thermal etch process. Forthe purposes of this disclosure a thermal etch process may utilize anetchant as a reactant in a thermal etch process. In some embodiments,the thermal etch process is performed with an etchant comprising H₂. Insome embodiments, an inert gas is co-flowed with the etchant during thethermal etch process.

In some embodiments, the film is etched with a plasma etch process. Forthe purposes of this disclosure, the plasma utilized in the plasma etchprocess is referred to as the etching plasma. In some embodiments, theetching plasma comprises one or more of H₂, HCl, Cl₂, or NF₃. In someembodiments, the etching plasma consists essentially of H₂. In someembodiments, the etching plasma consists essentially of HCl. In someembodiments, the etching plasma consists essentially of Cl₂. In someembodiments, the etching plasma consists essentially of NF₃. As used inthis manner, the term “consists essentially of” means that the etchingplasma is greater than or equal to about 95%, 98% or 99% of the statedspecies on an atomic basis. In some embodiments, an inert gas isco-flowed with the etching plasma during the plasma etch process.

The etching plasma can be a conductively-coupled plasma (CCP) orinductively coupled plasma (ICP) and can be a direct plasma or a remoteplasma. In some embodiments, the plasma has a power in the range ofabout 0 to about 2000 W. In some embodiments, the minimum plasma poweris greater than 0 W, 10 W, 50 W or 100 W.

The temperature during etch 130 can be any suitable temperaturedepending on, for example, the etch process, the etchant and/or theetching plasma(s) being used. In some embodiments, the etch temperatureis in the range of about 100° C. to 500° C., or in the range of about150° C. to about 450° C., or in the range of about 200° C. to about 400°C.

The processing chamber pressure during etch 140 can be in the range ofabout 100 mTorr to 300 Torr, or in the range of about 200 mTorr to about250 Torr, or in the range of about 500 mTorr to about 200 Torr, or inthe range of about 1 Torr to about 150 Torr.

After etching the method 100 reaches decision point 150. If the siliconfilm has reached a predetermined thickness on the first layer, thesubstrate optionally continues for further post-processing at 160. Ifthe silicon film has not reached a predetermined thickness on the firstlayer, the method returns to 120 for at least one additional cycle of“deposit”-“treatment”-“etch”.

Some embodiments include an optional post-processing 160 process. Thepost-processing 160 can be used to modify the deposited film or thesubstrate to improve some parameter of the film or substrate. In someembodiments, the post-processing 160 comprises annealing the film. Insome embodiments, post-processing 160 can be performed by in-situ annealin the same process chamber used for deposition 120, treatment 130and/or etch 140. Suitable annealing processes include, but are notlimited to, rapid thermal processing (RTP) or rapid thermal anneal(RTA), spike anneal, or UV cure, or e-beam cure and/or laser anneal. Theanneal temperature can be in the range of about 500° C. to 900° C. Thecomposition of the environment during anneal may include one or more ofH₂, Ar, He, N₂, NH₃, SiH₄, etc. The pressure during the anneal can be inthe range of about 100 mTorr to about 1 atm.

At any point during the methods described by this disclosure, thesubstrate can be heated or cooled. Such heating or cooling can beaccomplished by any suitable means including, but not limited to,changing the temperature of the substrate support and flowing heated orcooled gases to the substrate surface. In some embodiments, thesubstrate support includes a heater/cooler which can be controlled tochange the substrate temperature conductively. In one or moreembodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive gases, purge gases, reactants or plasmas. Rotatingthe substrate during processing (either continuously or in steps) mayhelp produce a more uniform deposition, treatment or etch by minimizingthe effect of, for example, local variability in gas flow geometries.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe invention. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in some embodiments,” “in one embodiment” or “in anembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the invention.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of selectively depositing a film, themethod comprising: providing a substrate having a first surface and asecond surface; exposing the substrate to a silane and a depositionplasma to deposit a silicon film on the first surface and the secondsurface, the silicon film having different properties on the firstsurface and on the second surface; exposing the silicon film to atreatment plasma to modify a structure, composition or morphology of thesilicon film on one or more of the first surface or the second surface,the treatment plasma comprising plasmas of one or more of Ar, He, or H₂;etching the film from the first surface and the second surface to removesubstantially all of the film from the second surface and leave at leastsome of the silicon film on the first surface; and repeating thedeposition, treatment and etching to form a film selectively on thefirst surface over the second surface.
 2. The method of claim 1, whereinthe first surface of the substrate consists essentially of silicon. 3.The method of claim 1, wherein the second surface of the substratecomprises one or more of silicon oxide, silicon nitride, glass or ametal.
 4. The method of claim 1, wherein the silane comprises at leastone species with the general formula Si_(n)H_(2n+2).
 5. The method ofclaim 3, wherein the silane consists essentially of SiH₄.
 6. The methodof claim 3, wherein the silane consists essentially of Si₂H₆.
 7. Themethod of claim 1, wherein the silane consists essentially of SiH₂Cl₂(dichlorosilane or DCS).
 8. The method of claim 1, wherein thedeposition plasma comprises of one or more of Ar, He, H₂ or N₂.
 9. Themethod of claim 1, wherein after deposition the crystallinity of thesilicon film differs on the first surface and the second surface. 10.The method of claim 1, wherein the treatment plasma consists essentiallyof a capacitvely coupled plasma.
 11. The method of claim 1, wherein thetreatment plasma consists essentially of an inductively coupled plasma.12. The method of claim 1, wherein after treatment the crystallinity ofthe deposited silicon film differs on the first surface and the secondsurface.
 13. The method of claim 1, wherein the film is etched using athermal etch process.
 14. The method of claim 1, wherein the film isetched using a plasma etch process.
 15. The method of claim 14, whereinthe plasma etch process utilizes a capacitvely coupled plasma.
 16. Themethod of claim 14, wherein the plasma etch process utilizes aninductively coupled plasma.
 17. The method of claim 14, wherein the filmis etched by a plasma comprised of H₂, HCl, Cl₂, or NF₃.
 18. The methodof claim 17, wherein the film is etched by a plasma consistingessentially of hydrogen.
 19. A method of selectively depositing a film,the method comprising: providing a substrate having a first surfaceconsisting essentially of silicon and a second surface comprised of atleast one different material; exposing the substrate to SiH₄ and ahydrogen plasma to deposit a silicon film on the first surface and thesecond surface, the silicon film having different properties on thefirst surface and on the second surface; exposing the silicon film to atreatment plasma to modify a structure, composition or morphology of thesilicon film on one or more of the first surface or the second surface,the treatment plasma comprising plasmas of one or more of Ar, He, or H₂;etching the film from the first surface and the second surface with athermal etch to remove substantially all of the film from the secondsurface and leave at least some of the silicon film on the firstsurface; and repeating the deposition, treatment and etching to form afilm selectively on the first surface over the second surface.
 20. Amethod of selectively depositing a film, the method comprising:providing a substrate having a first surface consisting essentially ofsilicon and a second surface comprised of at least one differentmaterial; exposing the substrate to SiH₄ and a hydrogen plasma todeposit a silicon film on the first surface and the second surface, thesilicon film having different properties on the first surface and on thesecond surface; exposing the silicon film to a treatment plasma tomodify a structure, composition or morphology of the silicon film on oneor more of the first surface or the second surface, the treatment plasmacomprising plasmas of one or more of Ar, He, or H₂; etching the filmfrom the first surface and the second surface with a plasma etch toremove substantially all of the film from the second surface and leaveat least some of the silicon film on the first surface; and repeatingthe deposition, treatment and etching to form a film selectively on thefirst surface over the second surface.